Modern sliding devices with onboard moving magnet linear motor are more shrinking in construction to find increased applications in diverse fields including semiconductor manufacturing equipments, various assembling machines, measuring instrument, and so on. The advanced sliding devices with onboard moving magnet linear motor are more needed to meet anticipated design specifications including compact and simple construction, high propulsion and accuracy in operation, high dust-proofing, durable and safety properties, ease in use and handling, maintenance-free working for lubrication of the linear motion guide units in which the sliding devices are incorporated, and less expensive production cost.
An example of the sliding devices with onboard moving-magnet linear motor is disclosed in, for example commonly assigned Japanese Patent Laid-Open No. 2005-333702. The prior sliding device is composed of an elongated flat bed, a flat table movable for reciprocation in a lengthwise direction by virtue of a linear motion guide unit, a field magnet of magnet segments lying on a first surface of the table confronting the bed in a way unlike magnetic poles are juxtaposed alternately in polarity in a traveling direction of the table, and an armature assembly having coreless armature windings of rectangular shape, which are installed on a second surface of the bed confronting the table in opposition to the field magnet in lengthwise direction. The bed and table are both made of magnetic material to establish magnetic circuits in part in a fashion the bed serves as a coil yoke while the table is as magnet yoke. On the surface of the table facing on to the bed, there is made a recess to set in place the field magnet of the magnet segments. Moreover, the recess is made to have a depth not more than a third a thickness of the field magnet. With the sliding device constructed as stated earlier, it is said that the table is constituted to make the stroke length larger, making the operating performance higher in traveling velocity and response, and further improving efficiency in production.
Another commonly assigned Japanese Patent Laid-Open No. 2002-10617 discloses the sliding device with onboard moving-magnet linear motor in which both the field magnet segments and armature windings are fewer in number than those in the sliding device recited earlier. The sliding device has the construction that makes it possible to rectify a magnetic flux pattern outside any one N-pole of forward and aft end poles of the field magnet, thereby sensing accurately a table position by a magnetic sensor element. Position of the table is monitored by the magnetic sensor element lying on the bed in opposition to the field magnet. Arranged outside the end pole of the field magnet is an auxiliary magnet unlike the associated end pole of the field magnet in polarity and less in range to have no effect on propulsion exerted on the moving table from the field magnet. The auxiliary magnet constructed as stated above serves to rectify the magnetic flux pattern at the end pole of the field magnet, which might otherwise deviate outwardly, thereby making sure of the same magnetic flux pattern as in the magnetic flux found at a boundary between any two adjacent magnetic poles in the field magnet. Thus, this auxiliary magnet makes it possible to sense any end pole of the field magnet with the same accuracy as at the boundary between the two adjacent poles in the field magnet.
A further another commonly assigned Japanese Patent Laid-Open No. 2001-352744 discloses the sliding device with built-in moving-magnet linear motor that is envisaged more accurate position control of the slider relatively to the bed as well as operating performance higher in traveling velocity and response ability. With this prior sliding device, the armature assembly is made to carry a three-phase conduction system while a driving circuit is transferred to the external driver to make the bed simple in construction, thereby resulting in reducing the sliding device in the overall height. A field magnet is made of rare earth permanent magnet to raise flux density, thereby ensuring the provision of high propulsion for the table. An encoder to monitor a position of the table is an optical encoder having an optical linear scale, which contributes to improvement in accurate monitoring. The construction in which the armature windings connected to cords, lines, and so on are placed on the stator side has less fear of causing dust and dirt, thus realizing clean environment.
The prior sliding device recited above proved successful in making the traveling stroke longer as well as in serving functions of high operating velocity and response, with parts including table, and so on which are designed to raise their manufacturing efficiency. Nevertheless, modern technology needs further advanced sliding devices that are more compact and simple in construction with high propulsion and accuracy in operation, high dust-proofing, durable and safety properties, ease in use and handling, maintenance-free working for lubrication of the linear motion guide units in which the sliding devices are incorporated, and less expensive production cost.
On the other side, a coreless armature and a linear motor using the same are disclosed in Japanese Patent Laid-Open No. 2006-60969 in which a base is made lengthwise thereof with dovetail groove while molding resin is charged in the dovetail groove to cause the resin to fill the dovetail groove, keeping the molded resin against falling away from the base to make certain of integral construction of the base with the armature windings embedded in the molded resin. The prior coreless armature and a linear motor using the same recited earlier, however, would entail a disadvantage of complicated manufacturing process to mold the armature windings integral with the base, which is previously cut with the dovetail groove.
In recent years, the sliding devices with onboard moving magnet linear motor are finding increased application in the industries where the moving object including the table and so on needs to travel across comparatively long stroke or interval. Thus, it remains a major challenge to upgrade the current sliding device to allow the table traveling over a long-range stroke or interval. To cope with this, it is needed to make the moving table as simpler as possible in construction and also as lighter as possible in weight to boost up the propulsion of the table and further get traveling velocity and response higher, even with small or compact in construction and better in production efficiency.